Early Puberty May Be Caused by Gene Mutation

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When a child enters puberty earlier than expected, doctors are
often at a loss to explain why. But now, researchers have
discovered a genetic mutation that they say causes some cases of
early puberty.

In the study, the researchers in Brazil screened the genomes of
32 people with early
puberty from 15 families. (Some cases of early puberty run in
families.)

Mutations in a gene called MKRN3 were found in 15 people from
five of the families. In all of these cases, the mutated MKRN3
gene was inherited from the father, the researchers said.

Early puberty, also called
precocious puberty, is puberty that occurs before age 8 in
girls, or age 9 in boys. Some cases are caused by brain tumors or
thyroid problems, but in many cases, a cause is not identified.

The average age of puberty onset for those with mutations in the
MKRN3 gene was about age 6 for girls, and age 8 for boys.

It's not clear exactly how MKRN3 plays a role in puberty, but it
may be involved in releasing the "brake" that normally prevents
puberty
from start ing, Dr. Ieuan Hughes, of Cambridge University in
the United Kingdom, wrote in an editorial accompanying the study.

Puberty begins when the brain starts producing higher levels of a
hormone called gonadotropin-releasing hormone. Mutations in the
MKRN3 gene may trigger an increase in levels of this hormone at
an earlier age, the researchers said.

To further investigate the role of MKRN3 in puberty, the
researchers studied the brains of mice. They found that levels of
MKRN3 gene expression were highest when the mice were young, and
reached a low point at the start of puberty, which provides more
evidence to tie this gene to puberty.

The study is published online today (June 5) in the New England
Journal of Medicine.